The potential of Fischer-Tropsch Synthesis (FTS) waxes as a feedstock for fluid catalytic cracking (FCC) has been evaluated with a once-through microriser reactor operating under realistic conditions. The highly paraffinic feedstock has a high reactivity and can be converted under industrial conditions to a high extent (> 90 wt%). The product distribution can be optimised by the process parameters and catalyst formulation. A high gasoline fraction (70 wt%) with a very low aromatics concentration can be obtained. As a result of the formation of i-paraffins, n-olefins and iolefins the gasoline is expected to possess an acceptable octane number. The reaction scheme derived predicts that the degree of branching in the paraffinic diesel-range product is lower than that of the gasoline-range product and that a relatively good diesel is expected. Due to the absence of sulfur and nitrogen in the feed extremely clean transportation fuels are obtained. The addition of ZSM-5 to an equilibrium catalyst allows the production of significant amounts of light olefins, in particular propene (16 wt%) and butenes (15 wt%). (c) 2005 Elsevier B.V. All rights reserved.